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Topic: Temperature Gauge Query... (Read 1897 times) |
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DippyD
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Temperature Gauge Query...
« on: Mar 21st, 2007, 8:54pm » |
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My temperature gauge after reaching a nice midway point drops off to just above the cold occasionally returning to it's 'correct position'. Any ideas what might be going on? My AC seems to be doing everything right except bringing warm air into the car! Do you think the two things are related?
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2.9 v12 estate
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taliban aka Cheekyboy2
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Re: Temperature Gauge Query...
« Reply #1 on: Mar 21st, 2007, 9:35pm » |
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mine does that, but it depends on speed etc, stuck in traffic it'll be midway, once i hit open road with cooler air it drops right down, as expected really....
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DippyD
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Re: Temperature Gauge Query...
« Reply #2 on: Mar 21st, 2007, 9:45pm » |
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Thanks, thats encouraging. Just got to get on top of that AirCon issue and I think I've nailed most of the big concerns. It's my first Scorp (picked it up a couple of days ago) ...and really enjoying it...
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harry.m1byt
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Re: Temperature Gauge Query...
« Reply #3 on: Mar 21st, 2007, 11:17pm » |
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That is odd, mine (2.9 12v) rises extremely rapidly upto the mid point and stays there steady as a rock - irrespective of outdoor temperature or running conditions. Which apart from the rapid rise, is what I would expect it to do.
If it did vary as you both seem to describe, I would be looking to change the thermost.
I have had cars in the past, where it was possible as the car warmed up from cold, to spot the opening of the stat on the gauge. It will slowly rise up to the set point of the stat, then as the stat opened it would fall back with the in rush of cooler water from the rad, then rise back again to settle at the mid way point for rest of the entire journey - but I'm not seeing the effect on the Scorp, it just goes up in one single movement and stops.
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August '95 2.9 12v auto Ultima -
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ferretmobile
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Re: Temperature Gauge Query...
« Reply #4 on: Mar 22nd, 2007, 12:25pm » |
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My guage used to go walkabouts... go up to mid way and then down again. I had the thermostat changed and the sender unit. Result, the guage goes up to midway and stays there regardless of weather conditions. My advise is to change these and this will solve your problem 
HTH, ferret. 
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taliban aka Cheekyboy2
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Re: Temperature Gauge Query...
« Reply #5 on: Mar 22nd, 2007, 12:50pm » |
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ahem, i dont see it as a problem, personally i think it should go up and down with driving conditions, as long as it stays within the 'normal running temp' area, stands to reason that if you're stuck in traffic on a warm day it will rise to the halfway mark and maybe the top third, then when you hit a motorway the velocity of cooler air will cause the temp to drop to the bottom third, unless its 90 degrees out like last summer. every motorbike i've owned does this, my current suzuki has digital temp gauge, if im stuck in traffic it'll rise to 107, the fan comes on, it drops too 100, then i hit open road, it drops to where it should be, around 78, its perfectly normal......
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DippyD
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Re: Temperature Gauge Query...
« Reply #6 on: Mar 22nd, 2007, 1:38pm » |
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Thanks. Think I'll try changing the Thermostat and see how that goes. Not sure again if this is related but just lost all electrics on dash and engine cut out whilst cruising down the motorway!! I have horn, hazards , central locking and that's about it, luckly managed to get into hard shoulder and bring the car to a safe postion. I've only had this a few days... Any ideas where i start? Already checked fuses for eec v ignition module and ignition lock.
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taliban aka Cheekyboy2
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Re: Temperature Gauge Query...
« Reply #7 on: Mar 22nd, 2007, 2:02pm » |
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before this happened have you disconnected the multiplug from the aux fuse box (drivers side) at any time? it sounds like a classic case of the multiplug not being seated correctly, everyones done it, you think its seated properly but it isnt, if it seats first time.....it aint seated properly, it has lugs on the rear as well as the front......
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DippyD
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Re: Temperature Gauge Query...
« Reply #8 on: Mar 22nd, 2007, 2:27pm » |
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Not technical enough to know what that multiplug looks like!! Sorry. I did add a relay (which was missing in the glove box)) to bring the 'Automatic Cruise Control' back to life along with a replacement ash tray and headlight switch. Car drove for about 80 miles or so before todays breakdown. Both fuse box covers were off at some stage over the past couple of days though. Are you suggesting that I need to replace that 'Multiplug'? Hoping it's that simple..
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Simmo
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Re: Temperature Gauge Query...
« Reply #9 on: Mar 22nd, 2007, 2:41pm » |
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Have you left the fusebox covers off at any time and possibly got water in them ? 'cos that will cause all manner of problems. The central (Drivers side) fusebox has a large multiplug connector which needs to be correctly seated as Taliban says..... he just got the name wrong  ....  ..... The auxillary fusebox is by the battery but they must both have the lids fitted and a battery cover in place to prevent water ingress. There are also drain holes in the bulkhead which need to be kept clear of leaves etc to allow water to escape. Check the wiring to the ashtray light to make sure is is not shorting and the multiplug connector the the light switch. Could be that in the process of changing these items something has been disturbed. May also be worth removing the relay to see if that helps. May be it was missing for a reason!.
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DippyD
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Re: Temperature Gauge Query...
« Reply #10 on: Mar 22nd, 2007, 3:05pm » |
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thanks simmo. I've only had the car a few days so don't know if the fuse compartments have been looked after. I'll remove the relay as suggested and check the wiring as you suggest. Somewhere there's a fuse blown and i cant see it!! Cant check anything till I've found that i guess... The previous owner had a new battery fitted a couple of months ago and I did notice after I'd broken down today that the negative cables weren't very well secured!
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scorpio_man
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Re: Temperature Gauge Query...
« Reply #11 on: Mar 22nd, 2007, 4:25pm » |
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hi there
also check the wiring behind the ashtray.
hth
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DippyD
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Re: Temperature Gauge Query...
« Reply #12 on: Mar 22nd, 2007, 5:34pm » |
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What would the symtoms be if it turns out the fuse box by the battery had been damaged by rain? There was only a plastic bag covering the battery and fuse box when i got it and it did rain last night down here in Bristol. 
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taliban aka Cheekyboy2
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Re: Temperature Gauge Query...
« Reply #13 on: Mar 23rd, 2007, 11:07pm » |
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all sorts can happen with that scenario craig, from the ignition light staying on when the key is removed to indicators staying on. get a battery cover, they cost under a tenner, you can dry the fuse boxes out with a hairdryer if the damage isnt too bad. make sure the drain holes under the battery area are unblocked, the fusebox on the other side tends to get leaves etc building up between it and the wing, clear this out as there is a vent slot in the fuse box that side......which is really helpful 
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DippyD
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Re: Temperature Gauge Query...
« Reply #14 on: Mar 23rd, 2007, 11:41pm » |
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Thanks again for the advice. Had a auto sparky look at the car this morning. Turns out it was just a 25 amp Ignition fuse that had blown and the 'multiplug not in correct position!!!. It was actually a new cruise control relay that was causing my strange head light problem. Have removed the relay and things have settled down. He also cleaned up some wiring behind the ash tray left behind from a hands free kit which he things may have contributed to the fuse blowing. Just got hold of a 7000 radio and I think I'll have him back to fit that aswel as check out the cruise control relay and a list of other electrical gremlins like no interior lighting, not back lighting on headlight contol switch or centre vent as well as door light not working!! But I think I'm getting there.
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harry.m1byt
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Re: Temperature Gauge Query...
« Reply #15 on: Mar 24th, 2007, 12:12pm » |
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on Mar 22nd, 2007, 12:50pm, taliban wrote:| ahem, i dont see it as a problem, personally i think it should go up and down with driving conditions, as long as it stays within the 'normal running temp' area, stands to reason that if you're stuck in traffic on a warm day it will rise to the halfway mark and maybe the top third, then when you hit a motorway the velocity of cooler air will cause the temp to drop to the bottom third, unless its 90 degrees out like last summer. every motorbike i've owned does this, my current suzuki has digital temp gauge, if im stuck in traffic it'll rise to 107, the fan comes on, it drops too 100, then i hit open road, it drops to where it should be, around 78, its perfectly normal...... |
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Over my lifetime I have personally owned around 30 cars and had additional exclusive use of around another 20 of so. None of them behaved as you describe above - without some fault being present either in the gauge or the cooling system.
The idea of the water jacket thermostat is to closely control the temperature within fairly tight limits. It doesn't open and close once up to temperature, it closes a little and opens up a little to control the flow through the system to exactly balance heat input against the available cooling. It is an analogue thing, rather than an on/off digital.
The cooling fans are a slightly different kettle of fish, in as much as they do have switching hysterisis of several degrees. So the changes of temperature would likely be noticed on the gauge itself. However this condition would be obvious from the noise made by the fans. Remember the cooling fans only provide the radiator with additional cooling capacity, so they could not normally produce the effect of cooling the water below the set point of the thermostat in the cooling system.
In other words from cold the indicated temperature should rise to the set point of the thermostat, stabilise there and not move throughout the entire journey. Should the weather be extremely hot and the car stationary, then it is possible the radiaotor may not be able to dispose of the heat quick enough - the indicated temperature may rise and the fans should cut in, bring the indicated temperature on the gauge back to its usual reading.
My experience of Granadas suggests that its cooling system capacity without the fans was such that they would never ever be needed in the UK - all assuming the system is working as it was designed to. Certainly I would only ever expect them to be needed whilst not moving, the air flow alone should be much more than enough.
The fans do however run slow speed, to provide cooling for the a/c 'radiator'.
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taliban aka Cheekyboy2
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Re: Temperature Gauge Query...
« Reply #16 on: Mar 24th, 2007, 9:56pm » |
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i wasnt really talking about the fans so much, i've never known them come come on, but i would expect the temp to rise and fall within the 'normal running temp limits' with driving conditions, i see it as basic physics; if you have a radiator (stationary) with hot fluid running through it it'll reach a temperature, and if the fluid is pumped through effectively and the rad is big enough the temp will be more or less stable, then blow air on it at a velocity of 70mph the temp will stabilise at a lower degree........
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sector-9
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Re: Temperature Gauge Query...
« Reply #17 on: Mar 24th, 2007, 11:04pm » |
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My diesel usually sits about half-way in normal use, rising to about 2/3rds when working hard (i.e. towing), and about 1/3rd when on the motorway for a while though it does fluctuate depending on engine load. If I let it roll in gear down a hill then the temperature can come right down to about 1/4, rising again as I give it some fuel. This appears to be normal for every 'old' diesel I've driven.
I disconnected the fan relay and timed how long it took for the temp warning light to come on if left idling. Basically it didn't unless I held it at a fast idle for about 15 minutes, though of course the fans would usually have cut in long before that point.
I don't see any of the above being a problem; whether the gauge rises and falls enough to be noticeable depends on how quickly it reacts to the changing sensor input - most deliberately react quite slowly so you won't see much movement unless the change is prolonged (same with the fuel gauge so it doesn't bounce up and down every time you brake or corner). If you want to see what's really happening in real-time with the coolant temperature then use the dashboard diagnostics and you'll see that it's constantly varying.
Darren
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harry.m1byt
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Re: Temperature Gauge Query...
« Reply #18 on: Mar 25th, 2007, 9:32am » |
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on Mar 24th, 2007, 11:04pm, sector-9 wrote:
I disconnected the fan relay and timed how long it took for the temp warning light to come on if left idling. Basically it didn't unless I held it at a fast idle for about 15 minutes, though of course the fans would usually have cut in long before that point. |
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Curious about my 2L petrol Granadas fans which I had never heard run in anger, on the hotest day of the year a few years ago and straight after a fast 100 mile run, I ran it into my garage blanking the radiator off and leving it idling whilst I kept an eye on it. It took it a good 30 minutes before the first fan kicked in and a lot of persuasion to get it hot enough for the second one to kick in. I knew the fans worked because I had tested them, but they just never came on in use.
A diesel is even more thermally efficient, which is why they take much longer to get up to temperature. My diesel takes ten miles at this time of year from cold, to get upto a stable temperature.
My 2.9 V12 Scorps gauge shoots up like a rocket, to the mid point and stays there. It has noticeably moved, before I have even got it out of the drive. By the time I get to the end of our street it is well on the way to the mid point and before I have driven half a mile to the boundary of the village it is up to temperature and settled [1] - never to budge again even a smidgen.
It settles with the needle horizontal, such that I can just see horizontal line of the ripple of water of the temperature symbol printed on the guage.
I agree there is some damping of the needle, probably the damping would take the needle one second to move from end to end of the guage. The damping is electronic, rather than by mechanical means (sticky grease) - obvious because the guages can move at full speed to indicate a faulty battery.
Checking the panel diagnostics diplay, I have seen that reading wandering up and down slightly, may be 2 or three degrees and quite quickly - Not enough nor slow enough to be even noticed on the normal guage.
Much of this aspect can depend on the engine design, where the temperature is measured and the quality of the thermostat.
[1] I was when I first got it, initially quite surprised by this cars speed of warm up and ability to produce heat in the cab from cold. My first thought was that it was heat being produced by the a/c working in reverse, though now I know it cannot do this. My gauge was not at that time working reliably due to a a poor connection at the engine multi-plug.
If my guage did indeed wonder about, I would be looking for the cause of its wondering - Sticking thermostat, cooling system choked up, or a problem with the guage itself or even a badly designed point of taking the measurement.
My cars maintenance prior to my buying it seems to have been impecable. Cooling system is spotlessly clean inside, not a sign of any sludge or rust etc. which can cause problems.
My motorcycle has a badly designed point of taking the measurement and its gauge never gets above the cool indication.
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sector-9
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Re: Temperature Gauge Query...
« Reply #19 on: Mar 25th, 2007, 5:15pm » |
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Don't forget the diesel has a smaller cooling capacity than the petrol ones (smaller radiator to accomodate the intercooler beside it) and the turbo will raise combustion temperatures very quickly when it spins up. It also has an oil-air cooling system to share some of the load.
I've found that the point where my thermostat opens is a little below the half-way mark (this is how far it gets initially from cold, before dropping down again and finally climbing to half way, and is where it settles during gentle cruising). Enthusiastic use of the turbo can push the gauge above half-way, but the temperature warning light has never come on whilst driving and I don't expect it to unless towing in a heat wave.
Darren
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